The present invention refers to a sealing device for a flanged bearing.
The present invention may be advantageously, but not exclusively, applied in the field of flanged bearings for the hub-bearing groups of vehicle wheels, to which the description which follows will make explicit reference without, however, losing any of its general nature.
Older types of hub-bearing groups present a sealing device made up of a metallic insert, which is anchored to the flanged end of the outer race of the bearing and is provided with a vulcanised rubber body, which extends from the free end of the insert itself.
The rubber body comprises a number of lips (usually from two to five) which extend to form seals on the surface on the inner race of the bearing and on the flanged surface of the hub which faces the above-mentioned lips.
Although sealing devices of the above-mentioned type have performed their function adequately for a number of years, they present some inconveniences, such as difficulties relating to assembly due to the relevant quantity of lips and the brief working life of the lips themselves.
A more recent version of this kind of sealing device still presents a metallic ring which is anchored to the flanged end of the outer race of the bearing and which is provided with a vulcanised rubber body which extends from the insert itself, but in this case the lips of the rubber body create a dynamic seal on the internal surface of a second metallic ring which is anchored to the inner race of the bearing.
This alternative permits a better, safer assembly of the various components and results in a better and more reliable dynamic seal between the two metallic rings, but there is no seal on the flanged section of the inner race of the bearing; as a result, various external agents such as mud, water and dust can easily enter via the free space between the sealing device and the hub flange, a factor which causes problems of alignment and centering between the bearing and the hub flange.
The aim of the present invention is to produce a sealing device for flanged bearings which reduces the difficulties regarding assembly and which permits an improvement in the working life of the bearings themselves, thus increasing their reliability.
Another aim of the present invention is to produce a sealing device which further improves the sealing characteristics on the hub-bearing group.
In order to fulfil these aims, and other aims which will be better explained in the following description, the present invention proposes the realisation of a sealing device for a flanged bearing in particular for a wheel hub in which the flanged ends of the outer race of the bearing have shrunk on to their internal surface the metallic rings of a sealing device; each metallic ring incorporates a rubber element which is suitable for forming a static seal on the outer race of the bearing; the rubber element extends towards the inner race of the bearing to then bend back towards the outside of the bearing itself with an appendix, which forms two seals on the internal surface of a second metallic ring; the latter is shrunk on to the external surface of the inner race of the bearing; the device is characterised by the fact that a rubber element is applied to the ring in correspondence to its free end, which is axially turned towards the inside of the device; the rubber element presents at least two lips, one of which forms a dynamic seal between the two races of the bearing together with the above-mentioned lips of the metallic ring, while the second lip forms a static seal of the ring against the surface of the inner race of the bearing which it faces.